Reply to comment on "Simple one-dimensional model of heat conduction which obeys Fourier's law"

In this reply we answer the comment by A. Dhar (cond-mat/0203077) on our Letter "Simple one dimensional model of heat conduction which obeys Fourier's law" (Phys. Rev. Lett. 86, 5486 (2001), cond-mat/0104453)Comment: 1 pag., 1 fi

The reform of Chinese state-owned ship crewing agencies and implications for China’s seafaring labour export

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Calculations of Hubbard U from first-principles

The Hubbard \emph{U} of the \emph{3d} transition metal series as well as SrVO$_{3}$, YTiO$_{3}$, Ce and Gd has been estimated using a recently proposed scheme based on the random-phase approximation. The values obtained are generally in good accord with the values often used in model calculations but for some cases the estimated values are somewhat smaller than those used in the literature. We have also calculated the frequency-dependent \emph{U} for some of the materials. The strong frequency dependence of \emph{U} in some of the cases considered in this paper suggests that the static value of \emph{U} may not be the most appropriate one to use in model calculations. We have also made comparison with the constrained LDA method and found some discrepancies in a number of cases. We emphasize that our scheme and the constrained LDA method theoretically ought to give similar results and the discrepancies may be attributed to technical difficulties in performing calculations based on currently implemented constrained LDA schemes.Comment: 24 pages, 13 figures; Submitted to Phys. Rev.

Obesity continues to be a major health risk for Danish seafarers and fishermen

Background. In addition to the well-known medical consequences of overweight, severe obesity may also constitute a safety problem on board a ship in case of an emergency. The purpose of this study was to determine the current extent of the problem of overweight among Danish seafarers and fishermen and to follow-up the situation since a previous survey. The aim was to identify the main target groups and determine the need for continuous intervention. Material and methods. Data on height and weight were obtained from the mandatory health examinations of seafarers and fishermen. A total of 2,101 seafarers were included in the study. Body Mass Index (BMI) was calculated for each individual seafarer. Data from two other surveys were used as reference. Results. A total of 1,379 (66%) of all tested subjects were overweight. Among the male officers and ratings, the relative risk of being overweight was 1.33 (1.25–1.38) and 1.30 (1.22–1.38), respectively. The relative risk for fishermen was 1.45 (1.25–1.66) and for maritime students and trainees 1.44 (1.25–1.66). The female seafarers had a relative risk of being overweight of 1.42 (1.23–1.65). There were a statistical significantly increased number of overweight merchant seafarers since 2001/2002. Discussion. The study shows that Danish merchant seafarers have a major and significantly increasing overweight problem. Among fishermen, overweight was even more frequent. Overweight constitutes a threat not only to their health, but also to their career at sea. The larger than expected incidence of overweight among new employees in the industry provides particular cause for concern. The causes of the problem are complex and interventions need to be broad. (Int Marit Health 2011; 62, 2: 98–103

Obesity continues to be a major health risk for Danish seafarers and fishermen

Background. In addition to the well-known medical consequences of overweight, severe obesity may also constitute a safety problem on board a ship in case of an emergency. The purpose of this study was to determine the current extent of the problem of overweight among Danish seafarers and fishermen and to follow-up the situation since a previous survey. The aim was to identify the main target groups and determine the need for continuous intervention. Material and methods. Data on height and weight were obtained from the mandatory health examinations of seafarers and fishermen. A total of 2,101 seafarers were included in the study. Body Mass Index (BMI) was calculated for each individual seafarer. Data from two other surveys were used as reference. Results. A total of 1,379 (66%) of all tested subjects were overweight. Among the male officers and ratings, the relative risk of being overweight was 1.33 (1.25–1.38) and 1.30 (1.22–1.38), respectively. The relative risk for fishermen was 1.45 (1.25–1.66) and for maritime students and trainees 1.44 (1.25–1.66). The female seafarers had a relative risk of being overweight of 1.42 (1.23–1.65). There were a statistical significantly increased number of overweight merchant seafarers since 2001/2002. Discussion. The study shows that Danish merchant seafarers have a major and significantly increasing overweight problem. Among fishermen, overweight was even more frequent. Overweight constitutes a threat not only to their health, but also to their career at sea. The larger than expected incidence of overweight among new employees in the industry provides particular cause for concern. The causes of the problem are complex and interventions need to be broad. (Int Marit Health 2011; 62, 2: 98–103

A study of factors associated with the ease of doing certain extension tasks

Call number: LD2668 .T4 1963 J46Master of Scienc

Velocity Correlations, Diffusion and Stochasticity in a One-Dimensional System

We consider the motion of a test particle in a one-dimensional system of equal-mass point particles. The test particle plays the role of a microscopic "piston" that separates two hard-point gases with different concentrations and arbitrary initial velocity distributions. In the homogeneous case when the gases on either side of the piston are in the same macroscopic state, we compute and analyze the stationary velocity autocorrelation function C(t). Explicit expressions are obtained for certain typical velocity distributions, serving to elucidate in particular the asymptotic behavior of C(t). It is shown that the occurrence of a non-vanishing probability mass at zero velocity is necessary for the occurrence of a long-time tail in C(t). The conditions under which this is a $t^{-3}$ tail are determined. Turning to the inhomogeneous system with different macroscopic states on either side of the piston, we determine its effective diffusion coefficient from the asymptotic behavior of the variance of its position, as well as the leading behavior of the other moments about the mean. Finally, we present an interpretation of the effective noise arising from the dynamics of the two gases, and thence that of the stochastic process to which the position of any particle in the system reduces in the thermodynamic limit.Comment: 22 files, 2 eps figures. Submitted to PR

New directions for hydrogen storage: Sulphur destabilised sodium aluminium hydride

Aluminium sulphide (Al2S3) is predicted to effectively destabilise sodium aluminium hydride (NaAlH4) in a single-step endothermic hydrogen release reaction. The experimental results show unexpectedly complex desorption processes and a range of new sulphur containing hydrogen storage materials have been observed. The NaAlH4-Al 2S3 system releases a total of 4.9 wt% of H2 that begins below 100°C without the need for a catalyst. Characterisation via temperature programmed desorption, in situ synchrotron powder X-ray diffraction, ex situ x-ray diffraction, ex situ Fourier transform infrared spectroscopy and hydrogen sorption measurements reveal complex decomposition processes that involve multiple new sulphur-containing hydride compounds. The system shows partial H2 reversibility, without the need for a catalyst, with a stable H2 capacity of ~1.6 wt% over 15 cycles in the temperature range of 200°C to 300°C. This absorption capacity is limited by the need for high H2 pressures (>280 bar) to drive the absorption process at the high temperatures required for reasonable absorption kinetics. The large number of new phases discovered in this system suggests that destabilisation of complex hydrides with metal sulphides is a novel but unexplored research avenue for hydrogen storage materials